The Cardiovascular system Flashcards
Components of the cardiovascular system
The heart
The blood vessels
The lymphatic system
The blood
Function of the heart
-Double pump
-Pump blood around the body
What are the two circulations?
Systemic- delivers oxygenated blood to tissues and delivers deoxygenated blood back to the heart
Pulmonary- Moves blood from the heart to the lungs and delivers oxygenated blood to the heart
Location of the heart
Lies in the mediasternum- a region that extends from the sternum to the vertebral column, from first rib to the diaphragm and between the lungs
The heart wall (4)
Pericardium
Epicardium
Myocardium
Endocardium
Pericardium
-Surrounds and protects the heart
- Provides lubrication to reduce friction between the heart and the surrounding structures.
Epicardium ( also known as visceral layer on pericardium)
External layer
- adheres to the myocardium of the heart
Myocardium
-Thickest layer of the heart
-Pumping action
-Composed of cardiac muscle tissue
Endocardium
-Innermost layer of the heart
-Provides a smooth lining for the chambers and valves
-Minimizes friction as blood passes through the heart
Right atrium
Receives blood from 3 veins:
-Superior vena cava
-Inferior vena cava
-Coronary sinus
Receives deoxygenated blood from the body from the IVC and SVC. This moves into the right ventricle through an AV valve
Right ventricle
-Receives deoxygenated blood from the right atria
-Contracts to pump blood via the pulmonary arteries to the lungs
(smaller than left ventricle due to the thickness of myocardium)
Left atrium
-Receives oxygenated blood from the lungs via the pulmonary veins
This moves into the left ventricle
Left ventricle
-Receives oxygenated blood from the left atria
-Contracts to pump oxygenated blood into the aorta to supply the systemic circulation
Atrioventricular valves (tricupsid and mitral valves)
-Situated between the atria and ventricle
-Help the pressure to build up in the right artium
-Help to stop blood once the blood has gone into the right ventricle (back flow)
Semi-lunar valves
-Situated in the pulmonary and aortic vessels
-Regulate flow leaving the heart
-Stop back flow
-Help pressure build up within the chamber before releasing into the next cardiac cycle phase
Sinoatrial node
-Collection of specialised cells (pacemaker cells), and is located in the upper wall of the right atrium
-Spontaneously generate electrical impulses
-The wave of excitation created by the SA node spreads via gap junctions across both atria, resulting in atrial contraction (atrial systole) – with blood moving from the atria into the ventricles.
-The rate at which the SA node generates impulses is influenced by the autonomic NS- Parasympathetic and Sympathetic
Atrioventricular node
- Located within the atrioventricular septum, near the opening of the coronary sinus.
-The AV node acts to delay the impulses, to ensure the atria have enough time to fully eject blood into the ventricles before ventricular systole.
-The wave of excitation then passes from the atrioventricular node into the bundle of His
The Bundle of His (atrioventricular bundle)
-Serves to transmit the electrical impulse from the AV node to the Purkinje fibres of the ventricles.
-Descends down the septum before dividing into the right bundle branch and left bundle branch
Purkinje fibres
-Are able to rapidly transmit cardiac action potentials from the bundle of His to the myocardium of the ventricles
The Coronary circulation
-Myocaridum has its own blood supply delivered via the Coronary arteries
-Left coronary artery splits into descending artery and left circumflex artery
-Right coronary artery splits into right descending artery and right marginal artery
Systole vs Diastole
Systole means contraction
Diastole means relaxation
Cardiac output
The volume of blood ejected from the ventricles each minute. Stroke volume X Heart rate
Stroke volume
Amount of blood ejected per beat
Heart rate
The amount of beats per minute
Regulation of stroke volume (3)
-Preload = a greater stretch on cardiac muscles fibres prior to contraction increases the force of contraction
-Contractility = is myocardinal contraction. The greater contraction of the myocardium will result in a stronger and more efficient pumping action of the heart
-Afterload = the amount of resistance the heart must overcome to open the aortic valve and push the blood volume out into the systemic circulation
Regulation of heart rate (2)
- Autonomic nervous system
- Chemical regulation
How does the autonomic nervous system regulate the heart rate?
- Medulla oblongata
-Receives input from receptors like:
Proprioceptors= monitor positions of limbs
Chemoreceptors= monitor chemical changes
Bororeceptors= monitor stretching of arteries and veins
How does Chemical regulation regulate the heart rate? (2)
- Hormones - adrenaline and noradrenaline
- Cations - sodium, potassium and calcium
Other factors that change the heart rate (5)
- Age
- Gender
- Body temp
- Physical fitness
- Cardiovascular disease
What is the basic structure of blood vessels? (3 layers)
- Tunica Interna = thin layer of endothelial cells. Forms the inner lining and is in direct contact with the blood
- Tunica Media = thick layer containing smooth muscle. Regulates the diameter of the lumen
- Tunica Externa = consists of elastic and collagen fibres. Outer covering. Helps anchor the vessels to surrounding tissues
What are the 5 major blood vessels (in order of size)
- Arteries
- Arterioles
- Veins
- Venules
- Capillaries
Arteries (2 types)
Elastic arteries= Largest in the body, thick tunica media dominated by elastic fibres, largest diameter, thinner walled
Muscular arteries= tunica media contains more muscle and fewer elastic fibres, thick walls
Arterioles
- Arterioles regulate the flow of blood into the capillary network of the boy’s tissues
Capillaries
- Connect the arterial outflow to the venous return
- They lack a tunica media and tunica externa as their walls are only one cell thick
- High network of capillaries increases the surface area available for rapid exchange of materials
Venules
- Groups of capillaries reunite within the tissues to form a venule
-Thin walls - Venules drain the capillary blood and begin to return the flow of blood back toward the heart
Veins
- Thin walls relative to their total diameter
- Tunica externa of veins is the thickest layer which consists of collagen and elastic fibres
- Contain valves
Vasoconstriction vs vasodilation
Vasoconstriction decreases the diameter of the lumen
Vasodilation increases the diameter
Blood pressure definition
Force of blood pushing against the vessel walls measured in millimeters (mmHg) of mercury
Systolic blood pressure vs Diastolic blood pressure
Systolic= highest pressure generated in the arteries during left ventricle contraction
Diastolic= lowest pressure generated in the arteries when the left ventricle is relaxed
Medial arterial pressure
The average blood pressure in the arteries
What are the factors that impact blood pressure? (3)
- Vascular resistance
- Venous return
- Velocity of blood flow
Vascular resistance. What is it? What is it determined by?
Is the opposition of blood flow caused by friction between the blood and the walls of the blood vessels.
Determined by: blood vessel lumen size, blood viscosity and total length of blood vessel
Venous return. What is it? How does it occur?
The volume of blood returning back to the heart through the systemic veins.
Occurs due to: pressure which is generated when the left ventricle contracts
Velocity blood flow. What is it? What is it determined by?
The speed at which the blood travels through the blood vessels.
Determined by: The diameter of the arteries and the cross sectional area of the arteries.
Physiological components are involved in regulating blood pressure… how? (4 things)
- Cardiovascular centre in the medulla oblongata
- Chemoreceptors
- Hormonal Regulation
- Autoregulation of blood flow
Formation of red blood cells. Where are they formed? and how? What regulates the production of RBC?
- Formed in the bone marrow
- Production starts in red bone marrow where stem cells (hemocytoblasts) differentiate into RBC and moved into the blood
- Regulated by the hormone erythropoietin secreted by the kidneys
- for example if oxygen levels are too low, kidneys release erythropoietin to increase the haemoglobin carrying capacity
Red blood cells (erythrocytes). What are they? What do they contain? Function?
- Tiny concaved discs
- Containing haemoglobin
- Function: transport oxygen between the lungs and tissues
White blood cells (luekocytes) Compared to RBC? Function? Examples?
- Larger than RBC
- Don’t contain haemoglobin like RBC
Function: to destroy and remove cellular debris and attack pathogens - Examples: Lymphocyte, monocytes, basophils
Platelets (Thrombocytes) What are they? Structure? Function?
- They are fragments of larger cells derived from bone marrow
- They have a sticky surface to allow them to accumulate (so they can form a clot)
Function: clotting and wound healing
What 3 major arteries branch from the aortic arch?
- Brachiocephalic trunk
- Left common carotoid artery
- Left subclavian artery (artery of the thorax)
Which regions does the brachiocephalic trunk supply?
- Head
- Neck
- Upper limb
- Thoracic wall
Which regions does the left common carotoid artery supply?
- Head
- Neck
Which regions does the left subclavian artery supply?
- Head
- Neck
- Left arm
Upper limb artery order
Subclavian, Axillary, Brachial, Radial and Ulna arteries
Lower limb artery order (pelvis and lower limb)
Common iliac, internal and external iliac, Femoral, Popliteal, Anterior and posterior tibial arteries
Upper limb drainage order veins (from digits to heart0
Digital veins, cephalic vein, basilic vein, radial and ulnar veins, brachial, axillary, subclavian, superior vena cava
Lower limb drainage order veins (toes to heart)
Digital veins, Tibial vein, Fibular vein, Popliteal vein, Femoral vein, Internal and external iliac veins, Common iliac veins, Inferior vena cava
